Integrated stratigraphic potential of the remarkably thick and complete Lower Jurassic sequence in the Mecsek Mts. (Hungary)

In the Early Jurassic, a more than 3 km thick transgressive sequence was deposited in a half-graben structure in the Mecsek Zone of the Tisza Mega-unit. The Mecsek was located on the NW European Neo-Tethyan margin during the Jurassic, where rifting was associated with the opening of the future Penninic Ocean. The Lower Jurassic syn-rift sequence starts with Hettangian to Sinemurian paralic coal series overlain by shallow marine mixed siliciclastic-carbonate deposits in the upper Sinemurian. Deepening of the basin resulted in the deposition of Allgäu facies-like sediments with common turbidite intercalation in the Pliensbachian and lowermost Toarcian. The early Toarcian Jenkyns Event is represented by a ~13m thick organic-rich black shale succession. After this event, the Allgäu facies continues to the upper Toarcian, characterised by increasing carbonate content and the absence of turbidites.
Significant variations are known in the thickness of the sequence from south to north. The main challenge lies in the fact that the syn-rift sequence is disintegrated by frequent and localised reactivation of tectonic activity. The thick succession underwent inversion phases, accompanied by intense folding and thrusting, during the Late Cretaceous and Neogene periods. The inversion mostly affected the thickest, southern occurrence of the succession.
Many classic descriptions, maps and interpretations were made based on petrography, sedimentary features, biostratigraphic markers and stratigraphic positions. However, a few aspects regarding the local and regional scale tectonic evolution remain controversial. The sequence has a high potential for obtaining high-resolution paleoenvironmental, stratigraphic and tectonic development information by applying new methods and approaches. These methods include cyclostratigraphy and astrochronology, bivalve shell geochemistry, element and carbon isotope chemostratigraphy and biostratigraphy based on new ammonite findings and calcareous nannofossils
A future project's main objective is to analyse and correlate selected time frames in detail by employing the aforementioned methods, in order to discover trends on local, regional and global scales. Cyclostratigraphy can be applied to the thick Pliensbachian-Toarcian marl with turbiditic sandstone intercalations to reveal orbital control on sedimentation, which may provide information for astrochronological models. Bivalve geochemistry will be used on Gryphea sp. calcite shells in order to investigate changes in seasonality and contribute to the global paleoclimatic database for the late Sinemurian. Carbon isotope and handheld XRF-based chemostratigraphy could be a useful method for analysing mixed siliciclastic and marly successions and establishing a potential basis for local and regional correlation in the absence of precise biostratigraphy. Structural aspects involve understanding rift-related structures and how they are affected by reactivation. Syn-rift geometry can be reconstructed in more detail at a regional level using kinematic restoration based on cross-sections, and at a local level by finding small-scale syn-sedimentary structures.